The present invention relates, in general, to the field of electrodializers and methods and concentrates made by a process in accordance therewith. More particularly, the present invention relates to an electrodializer, electrodialysis method and resultant concentrate solution which includes a probe for disposition within a vessel such as a test tube for removal of dissolved salts and other electrolytes from such solution by electrodialysis.
In the past, dissolved salts have normally been removed from solutions by various dialysis techniques, including dialysis tubing. In general, dialysis is the process of separating compounds or materials by the difference in their rates of diffusion through a colloidal semi-permeable membrane. Apparati for carrying out dialysis generally comprise two chambers separated by a semi-permeable membrane of parchment paper, latex, animal tissue or other colloid. A solution to be dialyzed is placed in one chamber and a pure solvent such as distilled water in the other. Crystalline substances tend to diffuse from the solution through the membrane and into the solvent more rapidly than amorphous substances, colloids or large molecules. Representative devices for carrying out dialysis include: U.S. Pat. No. 4,077,875 issued to Richard D. Kremer on Mar. 7, 1978 for a "Collodion Bag Concentration Accelerator and Sampler" and U.S. Pat. No. 4,196,085 issued to Calvin A. Saravis on Apr. 1, 1980 for a "Dialysis Solution Handling Device".
Likewise, it is also been known to apply an electrical potential to a fluid for purification thereof. See for example U.S. Pat. No. 672,229 issued to Jean A. Lacomme on Apr. 16, 1901 for an "Apparatus for the Purification of Water or Other Hygenic Purposes". Definitionally, however, when the process of dialysis is conducted under the influence of a difference in electrical potential, as from electrodes on opposite sides of a semi-permeable membrane, such process is termed electrodialysis.
In electrodialysis, the concentration and/or composition of electrolyte solutions is altered as a result of electromigration through colloidal semi-permeable membranes in contact with the solutions. The most common application of electrodialysis has been the desalinization of saline water by division into more concentrated and dilute portions. By the application of an electric current to a pair of electrodes, fresh water (diluate) and brine (concentrate) is created on opposite sides of the membrane. Representative patents illustrative of this technique include: U.S. Pat. No. 2,788,319 issued to Ralph G. Pearson on Apr. 9, 1957 for an "Ion Exchange Method and Apparatus"; U.S. Pat. No. Re 25,265 reissued to Paul Kollsman on Oct. 16, 1962 for "Reduction of Polarization in Liquid Streams Undergoing Deionization by Electrodialysis"; U.S. Pat. No. 3,657,105 issued to Willem In'T Veld on Apr. 18, 1972 for an "Electrodialysis Apparatus"; U.S. Pat. No. 3,697,410 issued to Allan M. Johnson et al. on Oct. 10, 1972 for an "Electrodialysis Demineralization Apparatus"; and U.S. Pat. No. 4,165,273 issued to Nikoali N. Azarov et al. on Aug. 21, 1979 for a "Device for Producing Deeply Desalted Water". Patents illustrative of a somewhat related electrolysis technique for controlling pH in various solutions include: U.S. Pat. No. 3,065,156 issued to Kennith W. Thompson on Nov. 20, 1962 for an "Electrolytic pH Regulator" and U.S. Pat. No. 4,152,215 issued to Yohzoh Yoshino et al. on May 1, 1979 for an "Apparatus for Controlling Small pH of Culture Solution for a Living Organism".
Other separation processes based on action within an electric field include electrophoresis. This process, related to electrostatic precipitation of dry materials, is based on the fact that particles which are essentially uncharged themselves, but which differ in their polarizability, are subjected to unbalanced forces when placed in non-uniform electric fields. An exemplary apparatus and method is described in U.S. Pat. No. 2,878,178 issued to Milan Bier on Mar. 17, 1959 for "Continuous Free-Boundary Flow Electrophoresis".
Heretofore, while the process of electrodialysis has long been known, conventional removal of dissolved salts from test tube solutions has been carried out by means of dialysis tubing due to the unavailability of satisfactory equipment to carry out the electrodialysis process. However, conventional dialysis is an inherently slow process and somewhat cumbersome to carry out. Moreover, in conventional dialysis valuable materials in solution may be lost such as small molecular weight units. Still further, some valuable material may also be lost due to denaturation because of extended dialysis tubing methods.